Blurry artifacts when exporting?!

[fritzunruh]

Hey there,

I'm working on a couple of film scans, which naturally contain a desirable amount of filmgrain.

When I'm exporting the final image as a TIF without any compression or resizing, said grain starts to muddy up real bad in a stripe pattern across the image. It doesnt inside the LR preview module itself, just on the export. I tried all given options to export, the problem persists with jpeg as well as with tif files, which I find very odd since tif is supposed to give me a lossless file, is it not?

I'm used to working with only the Camera RAW module inside of Adobe Bridge, but to troubleshoot I fired up LR and the problem seen in CRAW is exactly the same here - since CRAW gives more options to export eg PNG-files, I tried them as well - same story.

To clarify, this is not a problem of the scan, the original tif-file is flawless. I'm aware of funny artifacts when applying noise reduction in post, which I have done, but to an extend that looks good inside the preview on all levels of magnification.

Here's what it looks like.

Full image - Screengrab inside the LR preview - no artifacts whatsoever

Zoomed in to the sky - Screengrab inside the LR preview - no artifacts whatsoever

Zoomed in to the sky - Screengrab of the exported tif - smudgy blurred lines of grain, acceptable although still compressed looking grain in between

I'm aware that this is the very definition of pixel peeping, but since I'm planning on ordering an high quality, large print I know that this issue will darken my mood everytime I look at the result.

There has to be a way to get an image out of LR without any compressioneske artifacts, right?

Thanks for your help!

EDIT:

To add something I just discovered:

I tried to open the original source image from my scan in photoshop and reset all development settings upon import (Camera RAW pops up and wants settings, I just reversed everything and opened the image)

The issue comes up even before exporting the image, as soon as the source material is "touched" by the Camera RAW development module the image muds up, even inside of photoshop!

[fritzunruh]

To add something I just discovered:

I tried to open the original source image from my scan in photoshop and reset all development settings upon import (Camera RAW pops up and wants settings, I just reversed everything and opened the image)

The issue comes up even before exporting the image, as soon as the source material is "touched" by the Camera RAW development module the image muds up, even inside of photoshop!

[fritzunruh]

To add even more information: I realised that turning off hardware accelaration makes the problem appearent inside of the preview of LR as well. When I turn the hardware back on, I cant see the banding in the preview - unfortunatly when I then export to whatever format I can. Apparently the hardware acceleration is needed to prevent what is perceived as blurry, but is not used while rendering the image to export - is that just my system?

Current versions:
OS: MacOS Catalina 10.15.4 (up to date)
GPU: Radeon Pro 560 (A0.927, drivers linked to OS)
PS: 21.1.2 (up to date)
LR: 3.2.1 (up to date)
ACR: can' tell the version number, but up to date

[fritzunruh]

Nobody?